Acoustic analysis of gas compositions based on molecular relaxation features

The quantitative detection of gas compositions in mixture has been a challenge in the field of acoustic sensing. In this paper, we propose an acoustic gas sensing method using the molecular relaxation features to identify gas composition and determine composition concentration in excitable gases. The proposed method is based on the fact that the relaxation strength and relaxation time constitute relaxation absorption spectrum which characterizes the acoustic molecular relaxation process, and they can be synthesized only using two-frequency acoustic measurements. Then the applications of the method in the simple gas mixtures CO2-air and CH4-air, and the multiple component mixtures CO2-CH4-air demonstrate the feasibility, and the discussion of the sensing performance verifies the robustness. This work provides a more exact, feasible and practical method for the gas sensing applications. •We propose a simple, efficient and real-time acoustic gas sensing method via identifying molecular relaxation features of gas compositions.•The acoustic relaxation spectra are quantified into the characteristic relaxation strength and time.•The applications of the method in mixtures demonstrate its practicality, feasibility and robustness.